At the bottom of this article you'll be able to download the SMA's Quick Design Reference Tool (QDR) that provides string design and inverter selection recommendations in a simple, easy-to-use format.
Make sure to have your Smart Module datasheet equipped with TS4-L UHD-Core handy in order to accurately put in module parameters.
In case of uncertainty, Vlimit value can be equal or higher then:
Vlimit >= Vmp + 3.2 + (0.2 * Imp), round up to the nearest 0.1.
For example, 260W module with Vmp 30V and Imp 8.65A:
Vlimit >= 30 + 3.2 + (0.2 * 8.65) = 34.93
So, for that panel Vlimit can be equal or higher then 35.0V.